1. Field of the Invention
The present invention relates to a substrate supporting apparatus for supporting a substrate, and a surface potential measuring apparatus, a film thickness measuring apparatus, and a substrate inspection apparatus, each of which having the substrate supporting apparatus.
2. Description of the Background Art
In manufacturing of semiconductor devices, flat panel displays, and the like, various measurements or processings have been conventionally performed on surfaces of various substrates such as a semiconductor substrate and a glass substrate for a flat panel display. In apparatuses performing such measurements or processings, a substrate holding apparatus for holding a substrate by suction has been used as one of holding parts for holding a substrate.
For example, Japanese Patent Application Laid-Open No. 2003-316017 (Document 1) discloses an electron beam irradiation apparatus which has a spinning table on which a master disk of an optical disk is held, where an electron beam is applied onto the master disk which is rotated together with the spinning table to record information on the master disk. The electron beam irradiation apparatus further has a floating pad which has a ring-shaped air-permeable member formed of porous metal member and an electron beam irradiation head which is mounted on the floating pad. The floating pad ejects compressed air onto the upper surface of the master disk through the air-permeable member and thereby the floating pad floats in a noncontact manner over the master disk. With this structure, influences of unevenness in thickness, rotational vibrations of the master disk, or the like are reduced to keep a gap between the electron beam irradiation head and the master disk.
Since a substrate where various processings such as a film deposition or an annealing process are performed normally has a slight warpage, tilt, or the like, the substrate does not have a completely flat shape. Therefore, there is a limitation in improving the accuracy of various processings or inspections which are performed assuming that the substrate has a flat shape. In the electron beam irradiation apparatus of Document 1, it is aimed that influences such as unevenness in thickness of the master disk are reduced, however, there is a possibility unwanted particles adhere on a lower surface of the master disk or the lower surface is scratched because the master disk contacts the spinning table. Although the spinning table needs to be upsized with upsizing of the master disk, it is difficult to accurately form an upper surface of an upsized spinning table on which the master disk is placed and manufacturing cost for the spinning table is increased.